Potato and Prosciutto Croquettes

Ingredients

• ½ cup sour cream
• ¼ cup mayonnaise
• 1 tablespoon finely chopped chives
• 3 tablespoons fresh lemon juice
• ¼ teaspoon kosher salt
• Freshly ground black pepper
• 1½ pounds (2 large) russet potatoes
• 2 ounces prosciutto, finely diced
• ¾ cup finely grated Parmigiano-Reggiano
• 3 tablespoons finely chopped chives
• 3 tablespoons whole milk
• 2 tablespoons unsalted butter, melted
• 1 large egg
• Finely grated zest of 1 lemon
• ½ teaspoon kosher salt
• Freshly grated nutmeg
• 1 cup all-purpose flour
• 1¾ cups panko
• ½ cup all-purpose flour
• ¼ cup whole milk
• Neutral oil, such as canola or grapeseed, for frying
• Flaky sea salt
• Lemon wedges